Thursday, March 18, 2010

Conservation in Costa Rica

Since the 1990s, Costa Rica has been the site of one of the world’s most ambitious ecological restoration projects. Ecological restoration is the act of altering a habitat in order to return as much of it as possible to its original state. In the 1990s Costa Rica’s Tropical Forestry Initiative purchased 350 acres (1.4 km2) of land that had been cleared and used for ranching for the next 50 years. The initiative sought to restore a tropical wet forest (one receiving more than 100 inches [254 cm] of rainfall yearly) on the abandoned pastureland by planting 40,000 seedlings of a mix of 35 native tree species. One such preserve, named Los Arboles, will require from 100 to 800 years for the forest to mature, so the experiment remains in its earliest stages. Ecological restoration usually cannot restore all the native species by reintroducing them to an area, so in Los Arboles the best hopes are centered on a plan to nurture the planted seedlings and accelerate the growth of as many native species as possible. In order for restoration like Los Arboles to succeed, four important steps must occur: growth of the seedlings; dispersal of new seeds; germination of seeds; and avoidance of predation. Soil depleted of nutrients or areas with little available water increase the difficulty of restoring any forest.

A variety of techniques have been used in Costa Rica to assist natural processes in forest recovery. Forest restoration depends on seed dispersal by insects, rodents, and birds that eat seeds and eliminate undigested seeds in their waste in a new location. Restoration teams now help this process in two ways: by growing a healthy shrub understory and by providing perches for birds. Shrub understories provide habitat to attract birds, rodents, and insects, replenish soil, and keep aggressive grasses from hindering the growth of seedlings. Costa Rica’s young seedling trees needed time to reach a size suitable for perching of seed-dispersing birds, so workers built artificial perches. Other methods serve the same purpose as man-made perches. For instance, workers can plant young woody trees on the restoration’s perimeter to give birds a place to find shelter and roost. On restored rangelands, ranchers often leave a few stands of trees to provide shade for their cattle. These well-established trees already house insect and bird populations acclimated to the area, so they, too, aid the restoration.

In the northern part of Costa Rica, the biologist Daniel Janzen of the University of Pennsylvania has led a second restoration project in the tropical dry forest (which contains a distinct dry season) in Guanacaste National Park. Janzen and his students developed seedlings of the area’s native trees in his laboratory, then organized field trips from the United States to sow the seeds and plant seedlings. From the start Janzen included local students and farmers so that they could learn the restoration techniques. Since the local people participate in the recovery of their own natural resources for their long-term benefit, Guanacaste presents an example of biocultural restoration. This means both the environment and the local population receive some sort of recovery. In the community’s case, the residents received greater opportunity for earning higher income. Eventually, Costa Ricans will run the park with no outside influence.

Ecologists measure the progress of restoration by monitoring increases in number and diversity of species moving into the new habitat. Within the first decade of new growth in Costa Rica, woody plants and a diverse mixture of mammals, birds, and invertebrates began building populations. The Tropical Forestry Initiative recorded tree growth and species, finding that many trees grew 7.2 feet (2.2 m) per year and a canopy developed five years after planting seedlings. In addition, researchers counted more than 350 plant species that had become established in the new forest.

Restoration ecology would probably not be successful if left entirely to humans or entirely to nature, but the projects in Costa Rica prove they can work in tandem. Janzen described it this way in an essay he wrote for Science in 1998: “Why can’t the wild tropical species be left ‘out in the wild’ to fend for themselves? Because the wild is at humanity’s mercy. Humanity now owns life on Earth. . . . Until the Pleistocene, not more than a few thousandths of 1 percent of the Earth’s surface was ours. Today it all is. If we place those species anywhere other than in a human safe zone, they will continue in their downward spiral as grist in the human mill, just as they have for the past 10,000 years.” Though restoration ecology manipulates nature, it profits nature in the long term.

The Los Arboles project also relies on the success of its biocultural restoration activities. In 1997, David Knowles and A. Carl Leopold of the Tropical Forestry Initiative said in an ecology presentation, “A crucial part of this effort will be to spark interest among the local landowners. We are working with local landowners to encourage reforestation by providing them with seedlings, by participation in a local forestry association, and by interacting with local schools.” More than decade later, both of these forest restoration projects have engaged the local communities in the areas of restoration, ecotourism, and environmental education.

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In its broadest sense, science (from the Latin scientia, meaning "knowledge") refers to any systematic knowledge or practice. In its more usual restricted sense, science refers to a system of acquiring knowledge based on scientific method, as well as to the organized body of knowledge gained through such research.

Fields of science are commonly classified along two major lines: natural sciences, which study natural phenomena (including biological life), and social sciences, which study human behavior and societies. These groupings are empirical sciences, which means the knowledge must be based on observable phenomena and capable of being experimented for its validity by other researchers working under the same conditions.